[PATCH 7/8] writeback: sync old inodes first in background writeback
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From: Mel Gorman on 19 Jul 2010 09:20 From: Wu Fengguang <fengguang.wu(a)intel.com> A background flush work may run for ever. So it's reasonable for it to mimic the kupdate behavior of syncing old/expired inodes first. This behavior also makes sense from the perspective of page reclaim. File pages are added to the inactive list and promoted if referenced after one recycling. If not referenced, it's very easy for pages to be cleaned from reclaim context which is inefficient in terms of IO. If background flush is cleaning pages, it's best it cleans old pages to help minimise IO from reclaim. Signed-off-by: Wu Fengguang <fengguang.wu(a)intel.com> Signed-off-by: Mel Gorman <mel(a)csn.ul.ie> --- fs/fs-writeback.c | 19 ++++++++++++++++--- 1 files changed, 16 insertions(+), 3 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index d5be169..cc81c67 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -612,13 +612,14 @@ static long wb_writeback(struct bdi_writeback *wb, .range_cyclic = work->range_cyclic, }; unsigned long oldest_jif; + int expire_interval = msecs_to_jiffies(dirty_expire_interval * 10); + int fg_rounds = 0; long wrote = 0; struct inode *inode; - if (wbc.for_kupdate) { + if (wbc.for_kupdate || wbc.for_background) { wbc.older_than_this = &oldest_jif; - oldest_jif = jiffies - - msecs_to_jiffies(dirty_expire_interval * 10); + oldest_jif = jiffies - expire_interval; } if (!wbc.range_cyclic) { wbc.range_start = 0; @@ -649,6 +650,18 @@ static long wb_writeback(struct bdi_writeback *wb, work->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write; + if (work->for_background && expire_interval && + ++fg_rounds && list_empty(&wb->b_io)) { + if (fg_rounds < 10) + expire_interval >>= 1; + if (expire_interval) + oldest_jif = jiffies - expire_interval; + else + wbc.older_than_this = 0; + fg_rounds = 0; + continue; + } + /* * If we consumed everything, see if we have more */ -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |